[iUsedToCode]

Certainly. I heat a small flat (~35 m2) using just a AC unit and it works great: low costs, very comfortable. The only problem is increased dryness of the air.

But for a bigger place the setup is costly: you either need a couple units or a proper design, otherwise you'll end up with a only a portion of your home warm. Plus, AC units are still significantly more expensive than just a "trash-burner" type of furnace that is the most popular.

Electric heat should be the cheapest form. That would end a lot of air pollution that is a very serious health risk in Poland.